How Many Sensors Do You Need: Sizing a VIE Deployment

Three sensors per transformer. One gateway per cluster of up to 100 sensors within 100 meters. That is the formula. Every deployment scales from it.

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Why Three Sensors Per Transformer

A single sensor captures vibration data from the section of tank wall it is bonded to. Core and winding faults are not spatially uniform. A developing problem in one phase winding produces the strongest signal on the sensor nearest that phase. A single sensor on the wrong face may not capture a localized winding fault with adequate clarity.

Three sensors on three sides of the tank body give VIE coverage across all three phase windings. Each sensor captures the localized vibration from its nearest core phase. When a fault develops in a specific winding, the sensor closest to it shows the earliest and clearest signal. The other two sensors provide context and confirm whether the signal is localized or affecting the whole unit.

Oil and thermal conditions behave differently. Oil degradation and cooling problems affect the whole tank — they appear consistently across all three sensors. That consistency is itself diagnostic: a change that shows up on one sensor but not the others is more likely to be a localized mechanical event. A change that appears on all three simultaneously points toward oil or thermal conditions.

Sensors are placed on the vertical tank faces, away from radiator fins, at heights that give the thermal model a vertical gradient to work with. The front panel face is excluded to preserve access clearance for bushings and terminations.

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How Gateways Scale With the Fleet

One gateway handles up to 100 simultaneous sensors within a 100-meter BLE 5.0 range. The practical limit for most deployments is not the sensor count — it is the physical geometry of the site.

For a substation with five large power transformers in close physical proximity, the sensor count is 15 and one gateway is sufficient. For a substation with 20 transformers across a large footprint where some units are more than 100 meters from others, multiple gateways may be required to maintain BLE connectivity to all sensors.

For distributed fleets — transformers at different sites, substations across a service territory, or remote assets spread across a geographic area — each site requires at least one gateway. Gateway count follows site count, not just transformer count.

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Sizing Examples

Compact substation, 5 transformers:

15 sensors, 1 gateway. All transformers within 100 meters of each other and the gateway mounting point. Single LTE connection upstream.

Large substation, 20 transformers across a spread site:

60 sensors, 2 to 4 gateways depending on site geometry. Each gateway covers the sensors within its 100-meter radius. All gateways connect independently over LTE.

Distributed utility fleet, 50 transformers across 15 substations:

150 sensors, minimum 15 gateways (one per substation), more if individual substations have transformers spread beyond 100 meters. Each site operates independently and reports to the same myVIE platform view.

‍Single remote asset, 1 transformer:

3 sensors, 1 gateway. The economics of a single-asset deployment are most relevant for high-consequence assets — a critical substation transformer, an offshore platform unit, or a single large power transformer feeding an industrial facility where downtime cost is very high.

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What the Scoping Process Covers

Before hardware ships, VIE's team works through the deployment with the customer to confirm:

- Transformer count and site geometry for each location

- Gateway placement and connectivity options at each site (LTE coverage, Ethernet availability, Wi-Fi feasibility)

- Sensor placement priorities if physical access constraints require adjustments to the standard placement approach

- Total sensor and gateway count for the deployment

The output of that process is a deployment plan that specifies what ships, where it goes, and how each gateway connects upstream.